Formation and evolution of a carbide superlattice (SL) during C deposition on Mo have been studied using molecular beam epitaxy techniques. The ordering of the SL is energetically driven, such that the interplay between strain and surface energies determines the length scale of the SL. Surface precipitation of C occurs within a narrow range of SL spacing that appears to control the size and spacing of the precipitates leading to a possible mechanism for nucleation of single-walled carbon nanotubes.

• Received 23 January 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.015503